1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
#include <cstdio>
#include <map>

using namespace std;

int main(void)
{
    long long n, s;
    int m;
    map<long long, long long> occ;

    scanf("%lld%d%lld", &n, &m, &s);

    for (int i = 0; i < m; i++) {
        long long a, b;

        scanf("%lld%lld", &a, &b);
        occ[a] = b;
    }

    for (map<long long, long long>::iterator i = occ.begin(); i != occ.end(); ++i) {
        while (1) {
            map<long long, long long>::iterator j = i;
            if (++j != occ.end()) {
                if (j->first == i->second + 1) {
                    i->second = j->second;
                    occ.erase(j);
                    continue;
                }
            }
            break;
        }
    }

    map<long long, long long>::iterator f = occ.upper_bound(s);
    --f;

    long long l = f->first - 1;
    long long r = f->second + 1;
    long long p;

    if (s - l <= r - s)
        p = l;
    else
        p = r;

    if (p < 1)
        p = r;

    if (p > n)
        p = l;

    printf("%lld\n", p);

    return 0;
}